If it were only the battery, I'd replace it, but getting a new system will also scratch the itch to upgrade hardware specs. There's also some piece rattling around inside the case which must have broken off early on... (to my point about fragility compared to macbooks)

Consider (used) thinkpads. There are places that refurbish them, also selling you devices that just got out of their lease, due to the owner bailing out after only a few months. They are frequently available for half-price in good-as-new with still some warranty on them, which you don't need on the T and X series (not the carbon though). They need one screwdriver, for full disassembly.